Preparation of formic and acetic acids by oxidizing methylcyclohexane or paraffin wax in the presence of manganese bromide



United States Patent 3,247,249 I v V PREPARATION OF FORMIC AND ACETiC ACIDS BY {EXIDIZING METHYLCYCLOHEXANE OR FAJZAFFIN WAX IN THE PRESENCE OF MAN- GANESE EROMIDE Alfred Suffer, Bayside, and Robert S. Barker, Port Washington, N.Y., assignors to Halcon International, Inc, a corporation of Delaware No Drawing. Continuation of application Ser. No. 609,793, Sept. 14, 1956. This application July 9, 1962, Ser. No. 208,589

2 Claims. (Cl. 260-533) This application is a continuation of U.S. application Serial No. 609,793, filed September 14, 1956, now abandoned.

This application is concerned with oxidation processes. More particularly, it is concerned with a liquid phase oxidation process catalyzed by the conjoint presence of a metal and bromine. The invention is directed to the production of oxygenated compounds, particularly aliphatic acids.

The production of oxygenated com-pounds by oxidation is known. However, it has been discovered as a feature of this invention that utilization of a metal and bromine as catalyst in liquid phase oxidation makes possible higher reaction rates while at the same time very high oxygen absorption efficiencies are obtained. By varying the contact time and the temperature it is possible to obtain a wide variety of oxgenated products by means of the present invention.

In general, the invention is concerned with the oxidation of non-aromatic ieedstocks, which term is used herein to embrace non-aromatic hydro-carbons and oxygen containing non-aromatic hydrocarbons. These feedstocks are illustrated by inter alia alicyclic hydrocarbons such as cyclohexane and alkyl substituted cyclohexanes; alicyclic hydrocarbons containing a hetero-oxygen atom such as furane; parafiinic hydrocarbons such as alkanes, paratfin wax, and polyethylenes; and such oxygen containing non-aromatic hydrocarbons as, for example, the alcohols, such as ethyl alcohol, butyl alcohol, and higher alcohols; ketones such as acetone, methyl ethyl ketone, and higher ketones; aldehydes such as propionaldehyde and higher aldehydes, and the like. The foregoing are excellent starting materials when it is desired to produce, as hereinafter described, formic and acetic acids. When it is desired to produce other oxygenated compounds such as, for example, higher monoand dibasic aliphatic acids, it will be realized that the feedstock utilized must contain sufficient carbon atoms in the molecule to produce the desired acid. A wide variety of monoand dibasic aliphatic acids can be produced by the process of this invention such as, for example, glutaric, adipic, succinic, acetyl, valeric, suberic and azeleic acids. In general, there can be utilized as feedstocks alicyclic hydrocarbons as above described; paraiiin hydrocarbons, particularly the C to C compounds, olefins, and substituted olefin acids such as, for example, oleic acid. Oxidation of polyethylene can yield, for example, a wax-like product having properties resembling those of carnuba wax. Further, by proper control of conditions it is possible, utilizing the present invention, to epoxidize olefinic materials. Thus, controlled oxidation of oleic acid will yield 8-(1,2- epoxy decyl) octanoic acid. Analogously, controlled oxidation of propylene would yield propylene oxide.

in general, the invention contemplates oxidation of a non-aromatic hydrocarbon feedstock in the conjoint presence of a metal and bromine as a catalyst in which molecular oxygen, desirably air, is passed through the hydrocarbon which is maintained substantially in the liquid phase. Desirably there can be utilized in the reac- 3,247,249 Patented Apr. 19, 1966 tion mixture as a solvent or diluent, as the case may be, a mono-carboxylic acid having from 1 to 8 carbon atoms in the molecule.

As used herein, parts and percentages are by weight unless otherwise specified.

Example 1 Into a suitable pressure reactor having a corrosion resistant inner surface (e.g. glass, ceramic or corrosion resistant metal or alloy), equipped with agitating means such as a mechanical agitating device or gas flow agitating means, and with means for heating or cooling the contents thereof such as a coil or jacket, a condenser for refluxing non-aqueous condensate and some of the water to the reaction vessel, 21 gas inlet tube, and valved vent for passing oil inert gases and low boiling materials, there are charged:

parts methyl cyclohexane 150 parts acetic acid 1 part manganese bromide.

The reaction vessel is about half filled with the liquid mixture.

Air is passed into the reaction mixture at the rate of about 1000 volumes (measured at atmospheric pressure and about 27 C.) per volume of hydrocarbon per hour, while the reaction mixture is maintained at about 180 C. and about 350 p.s.i.g. Exit gas, after being passed through a condenser system to remove reactor constituents and to return them to the reactor, is vented from the system, in quantities sutiicient to maintain the desired pressure.

At the end of approximately 1 hour the reactor is cooled and the contents distilled through a 20-plate column to yield as products 46 parts formic acid and 164 parts aceti acid. It will be realized that the 164 parts acetic acid is composed of 150 parts starting material and 14 parts product.

Example 2 To the reactor of Example 1 there are charged:

parts paraffin wax (M.P. 5060 C.) 125 parts acetic acid 1 part manganese bromide.

Air is passed through at the rate of 1000 volumes (measured at atmospheric pressure and about 27 C.) per volume of hydrocarbon per hour while the reaction mixture is maintained at about 180 C. for 3 hours. Exit gas is vented as in Example 1. Distillation of the reactor contents as in Example 1 yields 62 parts formic acid and 137 parts acetic acid. It will be realized that the 137 parts acetic acid is composed of 125 parts starting material and 12 parts product.

Example 3 To the reactor of Example 1 there are charged:

100 parts methylcyclohexane 100 parts acetic acid /2 part cobalt bromide /2 part manganese bromide.

The reaction vessel is about half filled with the liquid mixture.

Air is passed into the reaction mixture at the rate of about 1000 volumes (measured at atmospheric pressure and about 27 C.) per volume of hydrocarbon per hour, while the reaction mixture is maintained at about C. and 50 p.s.i.g. for 2 hours. Exit gas is vented, as in Example 1.

The contents of the reactor are cooled and the materials boiling up to about C., i.e., acetic acid, un-

reacted methylcyclohexane, etc., are removed by distilation. The residue is a mixture of glutaric acid with lesser amounts of adipic, succinic, and acetylvaleric acids.

Example 4 Example 4 is repeated substituting for the benzoic acid there used as equal amount of caproic acid. Substantially similar results are obtained.

such as, for example, butyric acid, the reaction can be carried out in the range of about 50 to 145 C., desirably Desirable results are obtained with various modifications of the foregoing examples. Thus, the process can .be carried out in a batch, intermittent, or continuous manner. The feedstock can be anon-aromatic hydrocarbon or oxygen containing non-aromatic as disclosed above.

While it is not essential to utilize a mono-carboxylic acid having about 1 to 8 carbon atoms as a solvent or diluent, as the case may be, it is convenient to carry out the reaction utilizing these materials. For example, this allows excellent temperature control by variation of the pressure on the system. Additionally, when normally solid feedstocks are utilized use of a mono-carboxylic acid facilities material handling.

In general, the reaction can be carried out utilizing a metal and bromide as the catalyst. Particularly useful are the heavy metals shown in the Periodic Chart of Element on pages 56 and 57 of the Handbook of Chemistry, 8th edition, published by Handbook Publishers, Inc., Sandusky, Ohio, 1952. Of the heavy metal group those members having an atomic number not greater than 54 have been found suitable. However, the

tnetals outside the heavy metalgroup may also be employed. Excellent results are obtained by the utilization of a metal having an atomic number of 23-28 inclusive. Particularly excellent results are obtained with a metal of the group consisting of manganese, cobalt, nickel, chromium, vanadium, molybdenum, tungsten, tin, and cerium. The metal may be either as a single metal or as a combination of such metals. The metal may be added in elemental, combined or ionic form and similarly, the bromine may be added in elemental, combined or ionic form. As a source of bromine, ammonium bromide or other bromine compounds soluble in the reaction medium may be employed. Satisfactory results are obtained, for example, with potassium bromate, tetrabromoethane and benzyl bromide.

The metal may be supplied conveniently in the form .of metal salts. For example, the metal manganese may be supplied as the manganese salt of a lower aliphatic carboxylic acid, such as manganese acetate, in the form of an organic complex, of which mention may be made of the acetylacetonate, the S-hydroxy-quinolinate and the ethylene dlamine tetra-acetate, as well as manganese salts such as the borates, halides and nitrates which are also efiicacious. In general, the catalyst is utilized in amounts in the range of about 0.1 to based on the feedstock. Excellent results are obtained utilizing catalysts in the range of 0.4 to 5% and it is preferred to utilize 13% based on the feedstock.

The reaction temperature should be sufliciently high so that the desired oxidation reaction occurs, and yet not so high as to cause undesirable charring or formation of tars. Thus, the temperature in the range of about to 250 C. may be utilized. It will be realized that higher temperatures favor the production of lower aliphatic acids. For example, in the production of formic and acetic acids the reaction is generally carried out broadly in the range of from about 150 .to 250 C., desirably in the range of 160-220 C., and preferably in the range of 170-190 C. When it is desired to produce higher acids in the range of from about 150 to 250 C., desirably in the of to 120 C.

The mono-carboxylic acids which may be utilized as a solvent or diluent are illustrated, for example, by such as acetic, propionic, butyric, valeric, iso-butyric, phenylacetic, beta-ethoxy-acetic, benzoic, and the like acids.

Preferably, these acids do not contain hydrogen atoms attached to a tertiary carbon atom. These acids can be utilized in amounts up to about 20 parts per part of feedstock. While amounts in excess of this can be utilized such use is not desirable for economic reasons. Excellent results are obtained utilizing the mono-carboxylic acids in amounts of about /2 to 5 parts per part feedstock and it is preferred to utilize 1-3 parts per part of feedstock. While the foregoing examples illustrate the use of acetic acid, it will be realized that there can be substituted in the foregoing examples any monocarboxylic acid having 1 to 8 carbon atoms as described above and that substantially similar results are obtained.

As has been stated above, the pressure should be sufficient to maintain the feedstock in the liquid phase.

.Generally, the pressure is in the range of to 1500 p.s.i. g. and preferably is at least slightly above the boiling pressure of the mono-carboxylic acid utilized at the reaction temperature.

The oxygen used may be in the form of substantially 100% oxygen gas or in the form of gaseous mixtures containing lower concentrations of oxygen, e.g., down to about 20%, such as in air. Where the gaseous mixture contains a relatively lower concentration of oxygen, a correspondingly higher pressure or flow rate of the gas should be used, in order that a sufiicient amount (or partial pressure) of oxygen is actually fed into the reaction mixture.

\Vhile the foregoing examples have illustrated the utili zation of manganese and cobalt in the form of their bromides as the catalyst it will be realized that substitution of other metals, above described, in the foregoing examples yield similar results. For example, as a catalyst there may be utilized a combination of manganese acetate and ammonium bromide; powdered manganese metal and ammonium bromide; nickel bromide; cobalt acetate and ammonium bromide; manganese acetylacetonate and ammonium bromide; manganese 8-hydroxy quinonate and ammonium bromide; a manganese complex of ethylene diamine tetra-acetic acid and ammonium bromide; manganese borate and ammonium bromide; manganese chloride and ammonium bromide; manganese acetate and potassium bromate; manganese acetate and free bromine; manganeseacetate and tetra-bromoethane; and manganese acetate and benzyl bromide. Similarly, there may be utilized as a catalyst a material resulting from an admixture of 1 part cerium hydroxide, 1 part ammonium bromide and 50 parts of 20% hydrobromic acid, which mixture is evaporated to dryness. Additionally, tungstic acid, ammonium molybdenate or Raney nickel alloy may be treated similarly to cerium hydroxide as just described to yield an eifective catalyst. Amongst other metals which may be utilized conjointly with bromine to produce oxygenated compounds according to the process of this invention are beryllium, aluminum, bismuth, cadmium, iron, palladium, lead, neodymium,

and copper.

The oxygenated compounds produced according to the hours and it is preferred to operate in the range of 1-4 hours.

The process of this invention finds wide application. For example, utilization of cyclopropane as a feedstock gives good yields of formic acid utilizing the aforedescribed conditions for the production of such acid; on the other hand, utilizing temperatures in the range of 50 to 145 C. as described above, yields such desirable organic compounds as oxalic acid in addition to formic acid. Similarly, utilizing as a feedstock a terpene, such as commercial dipentene, yields, at the higher temperature range above described, formic and acetic acids while at the lower temperature range there are obtained oxygenated compounds illustrated, for example, by 4-rnethyl acetylhexene and beta-methyl glutaric acid. Further, utilizing as a feedstock 2-ethylhexanol, at the higher temperature there are obtained formic and acetic acids, While at the lower temperature there are obtained buty'ric and propionic acids. Utilization of an aldehyde such as, for example, iso-butyryl aldehyde gives isobutyric acid in addition to acetic and formic acids. Additionally, utilizing methyl iso-butyryl ketone, at higher temperatures there are obtained acetic and formic acids while at the lower temperatures there are obtained such acids as acetic and isobutyric acids.

In view of the foregoing discussions, variations and modifications of the invention will be apparent to one skilled in the art and it is intended to include within the invention all such variations and modifications except as do not come within the scope of the appended claims.

We claim:

1. In a process of oxidizing methyl cyclohexane where in a solution of methyl cyclohexane in acetic acid is introduced into a reaction zone, molecular oxygen is passed through said solution while maintaining a temperature between and 250 C., passing gaseous efiiuent from said reaction zone through a condenser system to remove unreacted constituents for recycle to said reaction zone, cooling said reaction zone, and distilling the contents of said reaction zone to yield a product comprising formic and acetic acids in excess of the amount of acetic acid originally introduced into said reaction zone, the improvement of oxidizing the methyl cyclohexane in the presence of 0.1 to 10% by weight of manganese bromide.

2. In a process of oxidizing paraffin wax wherein a solu tion of parafiin wax in acetic acid is introduced into a reaction zone, molecular oxygen is passed through said solution while maintaining a temperature between 50 and 250 C., passing gaseous efiiuent from said reaction zone through a condenser system to remove unreacted constituents for recycle to said reaction zone, cooling said reaction zone, and distilling the contents of said reaction zone to yield a product comprising formic and acetic acids in excess of the amount of acetic acid originally introduced into said reaction zone, the improvement of oxidizing the paraflin wax in the presence of 0.1 to 10% by weight of manganese bromide.

References Cited by the Examiner UNITED STATES PATENTS 2,265,948 12/1941 Loder 260-533 2,452,326 10/1948 Rust et al. 260-533 2,589,648 3/1952 Wadsworth 260533 2,825,740 3/1958 Armstrong et al. 260--533 2,833,816 5/1958 Saffer et al 260524 2,920,087 1/1960 Hay 260-533 LORRAINE A. WEINBERGER, Primary Examiner.

CHARLES B. PARKER, Examiner. 

1. IN A PROCESS OF OXIDIZING METHYL CYCLOHEXANE WHERE IN A SOLUTION OF METHYL CYCLOHEXANE IN ACETIC ACID IS INTRODUCED INTO A REACTION ZONE, MOLECULAR OXYGEN IS PASSED THROUGH SAID SOLUTION WHILE MAINTAINING A TEMPERATURE BETWEEN 50* AND 250*C., PASSING GASEOUS EFFLUENT FROM SAID REACTION ZONE THROUGH A CONDENSER SYSTEM TO REMOVE UNREACTED CONSTITUENTS FOR RECYCLE TO SAID REACTIO ZONE, COOLING SAID REACTION ZONE, AND DISTILLING THE CONTENTS OF SAID REACTION ZONE TO YIELD A PRODUCT COMPRISING FORMIC AND ACETIC ACIDS IN EXCESS OF THE AMOUNT OF ACETIC ACID ORIGINALLY INTRODUCED INTO SAID REACTION ZONE, THE IMPROVEMENT OF OXIDIZING THE METHYL CYCLOHEXANE IN THE PRESENCE OF 0.1 TO 10% BY WEIGHT OF MANGANESE BROMIDE.
 2. IN A PROCESS OF OXIDIZING PARAFFIN WAX WHEREIN A SOLUTION OF PARAFFIN WAX IN ACETIC ACID IS INTRODUCED INTO A REACTION ZONE, MOLECULAR OXYGEN IS PASSED THROUGH SAID SOLUTION WHILE MAINTAINING A TEMPERATURE BETWEEN 50* AND 250*C., PASSING GASEOUS EFFLUENT FROM SAID REACTION ZONE THROUGH A CONDENSER SYSTEM TO REMOVE UNREACTED CONSTITUENTS FOR RECYCLE TO SAID REACTION ZONE, COOLING SAID REACTION ZONE, AND DISTILLING THE CONTENTS OF SAID REACTION ZONE TO YIELD A PRODUCT COMPRISING FORMIC AND ACETIC ACIDS IN EXCESS OF HE AMOUNT OF ACETIC ACID ORIGINALLY INTRODUCED INTO SAID REACTION ZONE, THE IMPROVEMENT OF OXIDIZING THE PARAFFIN WAX IN THE PRESENCE OF 0.1 TO 10% BY WEIGHT OF MANGANESE BROMIDE. 